title: Hyaluronic acid production by recombinant Streptococcus thermophilus.
abstract: Generally recognized as safe, Streptococcus thermophilus was transformed using a plasmid expressing endogenous hyaluronic acid (HA) synthase genes. A single expression of hyaluronic acid synthase (hasA), uridine diphosphate-glucose dehydrogenase gene (hasB), or pyrophosphorylase gene (glmU) and double expression of hasA and hasB were attempted. A streptococcus-Escherichia coli shuttle vector, pBE31, was successfully transfected in S. thermophilus. The single expression of hasA or hasB allowed S. thermophilus to produce about 0.5-1.0 g/l HA. The strains coexpressing of hasA and hasB showed a markedly increased HA production (1.2g/l) which was six-fold increase compared with the wild-type strain. The maximum cell concentration and specific growth rate of each recombinant strain were lower than those of the wild-type strain; however, the specific production rate was more than 100-fold higher. Galactose concentration decreased in the coexpressing strain after depletion of lactose. The bacterial metabolism would be altered in order to achieve a higher production by changing the intracellular metabolism. The average molecular weight of HA (1.0 × 10(6) Da) was not affected by the expression of hasA and hasB. HA produced from recombinant strain could be an alternative material for medical, cosmetic and food utilization instead of HA from conventional pathogenic streptococci.
authors.affiliation: Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi-shi, Tokyo 186-8650, Japan. naoki-izawa@yakult.co.jp
authors.forename: Naoki
authors.initials: N
authors.lastname: Izawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Serata
authors.forename: Toshiro
authors.initials: T
authors.lastname: Sone
authors.forename: Takeshi
authors.initials: T
authors.lastname: Omasa
authors.forename: Hisao
authors.initials: H
authors.lastname: Ohtake
mesh_terms: D004926:Escherichia coli / Q000235:genetics; D005285:Fermentation; D005690:Galactose / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000235:genetics; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis*; D007218:Industrial Microbiology; D007785:Lactose / Q000378:metabolism; D008970:Molecular Weight; D010957:Plasmids; D048249:Streptococcus thermophilus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014162:Transfection; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000235:genetics
chemical_list: D006820:Hyaluronic Acid; D014533:Uridine Diphosphate Glucose Dehydrogenase; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases; D007785:Lactose; D005690:Galactose